Power Management Of A Radio Data Transceiver

• US 20110059779A1
• Filed: 09/08/2010
• Published: 03/10/2011
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Dominguez, Charles Francis, Vandwalle, Pierre, Haque, Tashbeeb, Thomas, Tito
• Granted Patent: US 8,351,996 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• CPC Class Codes: H04W 52/02 Power saving arrangements in wired systems H04L12/12; signaling of mobile application services, e.g. low battery notifications H04W4/20
• CPC Class Codes: H04W 52/0209 in terminal devices terminal devices per se H04W88/02
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 76/38 triggered by timers
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatuses for operating a wireless mobile station configured to communicate with a wireless access point are described. A first awake timer may be started in response to receiving a beacon signal from the wireless access point. The beacon signal may indicate that data is available or pending for the wireless mobile station. A second awake timer may be started in response to data received from the wireless access point. When the second awake timer expires, the wireless mobile station may return to the sleep state. In one embodiment, the first awake timer counts for a first period of time and the second awake timer counts for a second period of time which is shorter than the first period of time. The RF radio may be in a higher power state when the first and/or the second awake timers are counting. In one embodiment, the wireless mobile station and the wireless access points may be synchronized using target beacon transmission times of the beacon signal.

Claims

1. A method for operating a wireless mobile station which is configured to communicate with a wireless access point, the method comprising:

determining, at the wireless mobile station, an interval of time between successive target beacon transmission times (TBTT);

adjusting a period of time of an awake timer in response to the determining, wherein the adjusting is based on the interval of time.

2. The method as in claim 1 wherein the adjusting scales a default value for the period of time based upon the interval of time to produce an adjusted period of time.

3. The method as in claim 1 wherein the adjusting is performed through a lookup table.

4. The method as in claim 1 wherein the period of time determines when the awake timer expires and wherein a radio of the wireless mobile station is in a higher power state when the awake timer is counting prior to the awake timer expiring and wherein when the interval of time has a first value, the adjusting sets the period of time to a second value and wherein when the interval of time has a third value, the adjusting sets the period of time to a fourth value, and wherein the third value is larger than the first value and the fourth value is larger than the second value.

5. The method as in claim 4 wherein the wireless mobile station performs the adjusting adaptively in response to a change of the wireless access point.

6. The method as in claim 5 wherein the change of the wireless access point comprises a change from a first wireless access point, which is no longer in communication with the wireless mobile station, to a second wireless access point which is in communication with the wireless mobile station.

7. The method as in claim 1 wherein the method further comprises:

starting the awake timer in response to receiving data, the awake timer being a first awake timer;

starting a second awake timer in response to receiving a data pending message associated with a TBTT, wherein the first awake timer has a first period of time and the second awake timer has a second period of time which is longer than the first period of time.

8. The method as in claim 7 wherein the method further comprises:

starting a sleep timer in response to the expiration of one of the first awake timer or the second awake timer, the sleep timer being configured to cause the wireless mobile station to exit a lower power state for an RF radio at the expiration of the sleep timer and being configured to maintain the lower power state before the expiration of the sleep timer.

9. The method as in claim 8 wherein the sleep timer has one of a plurality of time periods based upon recent network activity.

10. A machine readable storage medium storing executable instructions which when executed by a data processing system cause the system to perform a method as in claim 1.

11. A method for operating a wireless mobile station which is configured to communicate with a wireless access point, the method comprising:

maintaining, for at least a period of time in the wireless mobile station, a sleep state in which a radio frequency (RF) radio, in the wireless mobile station, is in a low power state;

starting a first awake timer in response to receiving a beacon signal, from a wireless access point, that data is available for the wireless mobile station;

receiving the data at the wireless mobile station from the wireless access point;

starting a second awake timer in response to the receiving of the data, wherein when the second awake timer expires the wireless mobile station returns to the sleep state.

12. The method as in claim 11 wherein the first awake timer counts for a first period of time and the second awake timer counts for a second period of time which is shorter than the first period of time.

13. The method as in claim 12 wherein the radio is in a higher power state when the first awake timer is counting and has not expired, and the radio is in the higher power state when the second awake timer is counting and has not expired.

14. The method as in claim 13 wherein the beacon signal has target beacon transmission times (TBTTs) and wherein the wireless mobile station synchronizes itself with the wireless access point using the TBTTs.

15. The method as in claim 14 wherein the sleep state has one of a plurality of time periods for a corresponding plurality of sleep timers, and wherein the one of the plurality of time periods is selected by the wireless mobile station based on recent network activity.

16. A machine readable storage medium storing executable instructions which when executed by a data processing system cause the data processing system to perform a method as in claim 11.

17. A mobile station for use with a wireless access point, the mobile station comprising:

a radio frequency (RF) radio;

an antenna coupled to the RF radio;

a processor coupled to the RF radio, the processor configured to control a power state of the RF radio based upon (1) a state of a first sleep timer, and (2) a state of a first awake timer, and (3) a state of a second awake timer, and wherein the processor is configured to exit from a sleep state, during which the first sleep timer is counting, in response to the first sleep timer expiring, and wherein the processor is configured to cause the RF radio to listen for a beacon signal at a target beacon transmission time (TBTT) after the sleep timer expires and to return the RF radio to a low power state and to reset the first sleep timer when the beacon signal indicates no data available, and the processor is configured to cause the RF radio to listen for the beacon signal at a TBTT after the sleep timer expires and to cause the mobile station to enter a first awake state and to start the first awake timer when the beacon signal indicates data is available for the state, and wherein the processor is configured to enter a second awake state from the first awake state after data is received at the mobile station from the wireless access point.

18. The mobile station as in claim 17 wherein the first awake timer counts for a first period of time and the second awake timer counts for a second period of time which is shorter than the first period of time.

19. The mobile station as in claim 18 wherein the processor is configured to cause the mobile station to exit the second awake state and to enter the sleep state in response to the expiration of the second awake timer.

20. The mobile station as in claim 19 wherein the sleep state has one of a plurality of time periods for a corresponding plurality of sleep timers which comprise the first sleep timer and wherein the one of the plurality of time periods is selected by the mobile station based on recent network activity.

21. The mobile station as in claim 19 wherein the processor is one of (1) hardware logic;

(2) hardware logic and software;

(3) a set of processors.